Concentration of bismuth alloy



Aug. 9, 1932. w. c. SMITH CONCENTRATION OF BISMUTH ALLOY Filed Ju e 4, 1930 INVENTOR Wd//c'r 6. frz/'M ATTORNEY Patented Aug. 9, 1932 'UNITED STATES PATENT OFFICE WALTER C. SMITH, F IAPLEWOOD, NEW JERSEY, ABSIGNOB T0 CERRO DE PASQO COPPER CORPORATION, 0F NEW YORK, N. Y., A CORPORATION 0F NEW YGRK CONCENTRATION 0F BISMUTH ALLOY Application iled June 4, 1980. Serial No. 459,180.

This invention relates to the recovery or treatment of bismuth and more particularly to the concentration by selective oxidation of alloys or metal mixtures containing bisvA mllth.

In the concentration by selective oxidation of bismuth alloys, or metal mixtures containing bismuth, it has been the practice to submit the alloy or mixture to cu llation by subjecting the surface of the mo ten metal to the action of a stream-of air directed across the surface of such metal, Selective oxidation of bismuth allpys has also been conducted by introducing air into the'moltenalloy 15 through pipes having their ends submerged in the molten metal. A

By following either of the above methods, the oxidation is relatively slow and it is necessary to supply heat to the furnace by burning fuel, in order to maintain the temperature of the metal and slag suiciently high to allow the reactions to proceed. When the air is passed into the molten mass through pipes projecting into the metal, the deterioration of the pipes is very rapid, with a resultant excessive cost and a veryrapid'addition of impurities to the molten slag. Iron pipes are generally used and the iron acts as a reducing agent -on the oxides in the molten slag, thereby retarding the s eed of the concentration of bismuth. Furt ermore, in following this procedure it is impracticable to use 'a suieient number of pipes to supply an adequate amount .of oxygen to the molten mass. p

It is an object of this inventlon to avold the above diiculties and to provide an improved method and means for concentrating the bismuth in metal mixtures containing it. A A further object of this invention is to pro- 5 tration the invention will be described in Figure 2 is a section taken on the line 2-2 of y Figure 1. The furnace 1, having a basic lining 2, vis rotated upon the rollers 3, 3 in a clockwise direction, as viewed in Figure 2, to a position in which the tuyres 4 terminate above the level to be occupied by the molten metal. The. metal is then placed in the furnace and the latter is fired by the burners 5, 5 until the metal is reduced to a molten state. Air 1s then admitted to the tuyres under pressure through the supply pipe 6 which is plvoted at 7, and the furnace is then rotated in a counter-clockwise direction to the position shown in the drawing. The air is forced through the molten metal until the concentration by selective oxidation is compleeted, the gaseous products of combustion mg led to the stack through the outlet 8. The ends of the tuyres 4 should be protected from the molten metal and slag by a suitablelining material. By following this procedure, the lead, tin, arsenic, sulphur and antimony present in the molten mass will be oxidized and may be separated as fused slag or as fumes. The

oxidation of 'these impurities ma be con-- ducted so rapid] by this meth that the resultant heat wi at the required temperature. A layer of slag accumulates on the surface of the molten metal and ma be removed from time to time b rotating t e furnace and pouring -it olf t ou h the ope 8. Additional metal may added to t e furnace during the course of the operation and the heat generated by the oxidation will serve to melt this addted metal and to oxidize the impurities 1n 1 The temperature of the metal in the furnace may be controlled by regulating the air supply and the quantity of metal added to the furnace. For example, if the furnace becomes too hot the air sup ly may be cut down by a valve (not shown in the supply maintain the molten mass 1 lajdlleed to the furnace.

In using mi' improved process in a furnace having t e dimensions-of about 3 by 6 feet,.a charge consisting of a bullion containing about 10% bismuth may be concentrated 5 to 65% bismuth in about 24 hours as compared with 60 to 72 hours required to concentrate the same charge by the usual procedure. Furthermore, a saving of about l150 gallons of oil or the equivalent of other fuel, is accomplished at the same time.

It is apparent that modifications of my invention may be made to adapt it to diiferent uses and it is not intended to limit it to the particular embodiment described and l5 illustrated.

What I claim is v 1. A process for concentrating bismuth in a bismuth bullion containing as an impurity an 'element of the group comprising lead tin,

arsenic, sulphur and antimony, comprlsing passing air thro h the moltenmass at such a rate that the oxidation of impurities in the bullion will generate suiiicient heat to mantain vthe metal in a molten state.

l 2. In the concentration of bismuth in a bismuth bullion, containing as an impurity an element of the group comprising lead, tin,

arsenic, sulphur and antimony, the steps comprising melting the bismuth bullion and passing air through the molten metal to oxidize the impurities and maintain the mass in a molten state, and separating the oxidized impurities with the slag.

3. A prom for concentrating bismuth in a bullion qontaining lead and bismuth, comp h thebulliontoreduceittoa mlt'iltgg sithennd thereafter bubbling air 'through it at such a rate that the selective v oxidation of the metals associated with the 40 bismuth will maintain the mass in a molten State.

4. In the concentration of bismuth in a bullion containing lead and about 10% hismuth the steps com rising heating the mass to reduce it to a mo ten condition and thereafter cutting off the external heat and passing air through the molten'mass at such a rate as to maintain it in a molten condition.

5. A process for concentrating bismuth in 5 a bullion containing lead andbismuth, comprising heating the bullion to reduce it to a4 molten mass and thereafter bubbling air through it at such a rate that the selective oxidation of metals associated with the bismuth will maintain the mass in a molten condition, removing the si? containing the oxidized metals separated om the bismuth and adding further bullion to the molten mass and melting the addedV bullion by the heat 0 fromthe oxldation.

In testimony whereof, I have signed my name to this specication, this 26th day o f Y May, 1930. A u WALTER C. SMITH. 

